package com.cbg.base.utils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Component;
import java.util.Objects;
/**
 * 工具类:从Spring容器获取bean
 * 
 * @author chenbing
 * @时间 2018年6月7日 下午1:47:41
 */
@Component
@Lazy(false)
public class SpringContextHolder implements ApplicationContextAware, DisposableBean {
	private static ApplicationContext applicationContext = null;

	private static Logger logger = LoggerFactory.getLogger(SpringContextHolder.class);

	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型
	 */
	public static <T> T getBean(Class<T> requiredType) {
		assertContextInjected();
		return applicationContext.getBean(requiredType);
	}

	@SuppressWarnings("unchecked")
	public static <T> T getBean(String name) {
		assertContextInjected();
		return (T) applicationContext.getBean(name);
	}

	/**
	 * 取得存储在静态变量中的ApplicationContext
	 */
	public static ApplicationContext getApplicationContext() {
		return applicationContext;
	}

	/**
	 * 实现ApplicationContextAware接口, 注入Context到静态变量中
	 */
	@Override
	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
		SpringContextHolder.applicationContext = applicationContext;
	}

	/**
	 * 实现DisposableBean接口, 在Context关闭时清理静态变量
	 */
	@Override
	public void destroy() throws Exception {
		SpringContextHolder.clearHolder();
	}

	/**
	 * 清除SpringContextHolder中的ApplicationContext为Null
	 */
	private static void clearHolder() {
		if (logger.isDebugEnabled()) {
			logger.debug("清除SpringContextHolder中的ApplicationContext:" + applicationContext);
		}
		applicationContext = null;
	}

	/**
	 * 非空检查
	 */
	private static void assertContextInjected() {
		Objects.requireNonNull(applicationContext,"applicaitonContext属性未注入");
	}
}
